examples/sharing.c - third_party/glfw - Git at Google

 //========================================================================
 // Context sharing example
 // Copyright (c) Camilla Löwy <elmindreda@glfw.org>
 //
 // This software is provided 'as-is', without any express or implied
 // warranty. In no event will the authors be held liable for any damages
 // arising from the use of this software.
 //
 // Permission is granted to anyone to use this software for any purpose,
 // including commercial applications, and to alter it and redistribute it
 // freely, subject to the following restrictions:
 //
 // 1. The origin of this software must not be misrepresented; you must not
 //    claim that you wrote the original software. If you use this software
 //    in a product, an acknowledgment in the product documentation would
 //    be appreciated but is not required.
 //
 // 2. Altered source versions must be plainly marked as such, and must not
 //    be misrepresented as being the original software.
 //
 // 3. This notice may not be removed or altered from any source
 //    distribution.
 //
 //========================================================================

 #define GLAD_GL_IMPLEMENTATION
 #include <glad/gl.h>
 #define GLFW_INCLUDE_NONE
 #include <GLFW/glfw3.h>

 #include <stdio.h>
 #include <stdlib.h>

 #include "linmath.h"

 static const char* vertex_shader_text =
 "#version 110\n"
 "uniform mat4 MVP;\n"
 "attribute vec2 vPos;\n"
 "varying vec2 texcoord;\n"
 "void main()\n"
 "{\n"
 "    gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
 "    texcoord = vPos;\n"
 "}\n";

 static const char* fragment_shader_text =
 "#version 110\n"
 "uniform sampler2D texture;\n"
 "uniform vec3 color;\n"
 "varying vec2 texcoord;\n"
 "void main()\n"
 "{\n"
 "    gl_FragColor = vec4(color * texture2D(texture, texcoord).rgb, 1.0);\n"
 "}\n";

 static const vec2 vertices[4] =
 {
     { 0.f, 0.f },
     { 1.f, 0.f },
     { 1.f, 1.f },
     { 0.f, 1.f }
 };

 static void error_callback(int error, const char* description)
 {
     fprintf(stderr, "Error: %s\n", description);
 }

 static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
 {
     if (action == GLFW_PRESS && key == GLFW_KEY_ESCAPE)
         glfwSetWindowShouldClose(window, GLFW_TRUE);
 }

 int main(int argc, char** argv)
 {
     GLFWwindow* windows[2];
     GLuint texture, program, vertex_buffer;
     GLint mvp_location, vpos_location, color_location, texture_location;

     glfwSetErrorCallback(error_callback);

     if (!glfwInit())
         exit(EXIT_FAILURE);

     glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
     glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);

     windows[0] = glfwCreateWindow(400, 400, "First", NULL, NULL);
     if (!windows[0])
     {
         glfwTerminate();
         exit(EXIT_FAILURE);
     }

     glfwSetKeyCallback(windows[0], key_callback);

     glfwMakeContextCurrent(windows[0]);

     // Only enable vsync for the first of the windows to be swapped to
     // avoid waiting out the interval for each window
     glfwSwapInterval(1);

     // The contexts are created with the same APIs so the function
     // pointers should be re-usable between them
     gladLoadGL(glfwGetProcAddress);

     // Create the OpenGL objects inside the first context, created above
     // All objects will be shared with the second context, created below
     {
         int x, y;
         char pixels[16 * 16];
         GLuint vertex_shader, fragment_shader;

         glGenTextures(1, &texture);
         glBindTexture(GL_TEXTURE_2D, texture);

         srand((unsigned int) glfwGetTimerValue());

         for (y = 0;  y < 16;  y++)
         {
             for (x = 0;  x < 16;  x++)
                 pixels[y * 16 + x] = rand() % 256;
         }

         glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 16, 16, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, pixels);
         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

         vertex_shader = glCreateShader(GL_VERTEX_SHADER);
         glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
         glCompileShader(vertex_shader);

         fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
         glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
         glCompileShader(fragment_shader);

         program = glCreateProgram();
         glAttachShader(program, vertex_shader);
         glAttachShader(program, fragment_shader);
         glLinkProgram(program);

         mvp_location = glGetUniformLocation(program, "MVP");
         color_location = glGetUniformLocation(program, "color");
         texture_location = glGetUniformLocation(program, "texture");
         vpos_location = glGetAttribLocation(program, "vPos");

         glGenBuffers(1, &vertex_buffer);
         glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
         glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
     }

     glUseProgram(program);
     glUniform1i(texture_location, 0);

     glEnable(GL_TEXTURE_2D);
     glBindTexture(GL_TEXTURE_2D, texture);

     glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
     glEnableVertexAttribArray(vpos_location);
     glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
                           sizeof(vertices[0]), (void*) 0);

     windows[1] = glfwCreateWindow(400, 400, "Second", NULL, windows[0]);
     if (!windows[1])
     {
         glfwTerminate();
         exit(EXIT_FAILURE);
     }

     // Place the second window to the right of the first
     {
         int xpos, ypos, left, right, width;

         glfwGetWindowSize(windows[0], &width, NULL);
         glfwGetWindowFrameSize(windows[0], &left, NULL, &right, NULL);
         glfwGetWindowPos(windows[0], &xpos, &ypos);

         glfwSetWindowPos(windows[1], xpos + width + left + right, ypos);
     }

     glfwSetKeyCallback(windows[1], key_callback);

     glfwMakeContextCurrent(windows[1]);

     // While objects are shared, the global context state is not and will
     // need to be set up for each context

     glUseProgram(program);

     glEnable(GL_TEXTURE_2D);
     glBindTexture(GL_TEXTURE_2D, texture);

     glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
     glEnableVertexAttribArray(vpos_location);
     glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
                           sizeof(vertices[0]), (void*) 0);

     while (!glfwWindowShouldClose(windows[0]) &&
            !glfwWindowShouldClose(windows[1]))
     {
         int i;
         const vec3 colors[2] =
         {
             { 0.8f, 0.4f, 1.f },
             { 0.3f, 0.4f, 1.f }
         };

         for (i = 0;  i < 2;  i++)
         {
             int width, height;
             mat4x4 mvp;

             glfwGetFramebufferSize(windows[i], &width, &height);
             glfwMakeContextCurrent(windows[i]);

             glViewport(0, 0, width, height);

             mat4x4_ortho(mvp, 0.f, 1.f, 0.f, 1.f, 0.f, 1.f);
             glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
             glUniform3fv(color_location, 1, colors[i]);
             glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

             glfwSwapBuffers(windows[i]);
         }

         glfwWaitEvents();
     }

     glfwTerminate();
     exit(EXIT_SUCCESS);
 }
	//========================================================================
	// Context sharing example
	// Copyright (c) Camilla Löwy <elmindreda@glfw.org>
	//
	// This software is provided 'as-is', without any express or implied
	// warranty. In no event will the authors be held liable for any damages
	// arising from the use of this software.
	//
	// Permission is granted to anyone to use this software for any purpose,
	// including commercial applications, and to alter it and redistribute it
	// freely, subject to the following restrictions:
	//
	// 1. The origin of this software must not be misrepresented; you must not
	// claim that you wrote the original software. If you use this software
	// in a product, an acknowledgment in the product documentation would
	// be appreciated but is not required.
	//
	// 2. Altered source versions must be plainly marked as such, and must not
	// be misrepresented as being the original software.
	//
	// 3. This notice may not be removed or altered from any source
	// distribution.
	//
	//========================================================================

	#define GLAD_GL_IMPLEMENTATION
	#include <glad/gl.h>
	#define GLFW_INCLUDE_NONE
	#include <GLFW/glfw3.h>

	#include <stdio.h>
	#include <stdlib.h>

	#include "linmath.h"

	static const char* vertex_shader_text =
	"#version 110\n"
	"uniform mat4 MVP;\n"
	"attribute vec2 vPos;\n"
	"varying vec2 texcoord;\n"
	"void main()\n"
	"{\n"
	" gl_Position = MVP * vec4(vPos, 0.0, 1.0);\n"
	" texcoord = vPos;\n"
	"}\n";

	static const char* fragment_shader_text =
	"#version 110\n"
	"uniform sampler2D texture;\n"
	"uniform vec3 color;\n"
	"varying vec2 texcoord;\n"
	"void main()\n"
	"{\n"
	" gl_FragColor = vec4(color * texture2D(texture, texcoord).rgb, 1.0);\n"
	"}\n";

	static const vec2 vertices[4] =
	{
	{ 0.f, 0.f },
	{ 1.f, 0.f },
	{ 1.f, 1.f },
	{ 0.f, 1.f }
	};

	static void error_callback(int error, const char* description)
	{
	fprintf(stderr, "Error: %s\n", description);
	}

	static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
	{
	if (action == GLFW_PRESS && key == GLFW_KEY_ESCAPE)
	glfwSetWindowShouldClose(window, GLFW_TRUE);
	}

	int main(int argc, char** argv)
	{
	GLFWwindow* windows[2];
	GLuint texture, program, vertex_buffer;
	GLint mvp_location, vpos_location, color_location, texture_location;

	glfwSetErrorCallback(error_callback);

	if (!glfwInit())
	exit(EXIT_FAILURE);

	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 2);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 0);

	windows[0] = glfwCreateWindow(400, 400, "First", NULL, NULL);
	if (!windows[0])
	{
	glfwTerminate();
	exit(EXIT_FAILURE);
	}

	glfwSetKeyCallback(windows[0], key_callback);

	glfwMakeContextCurrent(windows[0]);

	// Only enable vsync for the first of the windows to be swapped to
	// avoid waiting out the interval for each window
	glfwSwapInterval(1);

	// The contexts are created with the same APIs so the function
	// pointers should be re-usable between them
	gladLoadGL(glfwGetProcAddress);

	// Create the OpenGL objects inside the first context, created above
	// All objects will be shared with the second context, created below
	{
	int x, y;
	char pixels[16 * 16];
	GLuint vertex_shader, fragment_shader;

	glGenTextures(1, &texture);
	glBindTexture(GL_TEXTURE_2D, texture);

	srand((unsigned int) glfwGetTimerValue());

	for (y = 0; y < 16; y++)
	{
	for (x = 0; x < 16; x++)
	pixels[y * 16 + x] = rand() % 256;
	}

	glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, 16, 16, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, pixels);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
	glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

	vertex_shader = glCreateShader(GL_VERTEX_SHADER);
	glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
	glCompileShader(vertex_shader);

	fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
	glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
	glCompileShader(fragment_shader);

	program = glCreateProgram();
	glAttachShader(program, vertex_shader);
	glAttachShader(program, fragment_shader);
	glLinkProgram(program);

	mvp_location = glGetUniformLocation(program, "MVP");
	color_location = glGetUniformLocation(program, "color");
	texture_location = glGetUniformLocation(program, "texture");
	vpos_location = glGetAttribLocation(program, "vPos");

	glGenBuffers(1, &vertex_buffer);
	glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
	}

	glUseProgram(program);
	glUniform1i(texture_location, 0);

	glEnable(GL_TEXTURE_2D);
	glBindTexture(GL_TEXTURE_2D, texture);

	glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
	glEnableVertexAttribArray(vpos_location);
	glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
	sizeof(vertices[0]), (void*) 0);

	windows[1] = glfwCreateWindow(400, 400, "Second", NULL, windows[0]);
	if (!windows[1])
	{
	glfwTerminate();
	exit(EXIT_FAILURE);
	}

	// Place the second window to the right of the first
	{
	int xpos, ypos, left, right, width;

	glfwGetWindowSize(windows[0], &width, NULL);
	glfwGetWindowFrameSize(windows[0], &left, NULL, &right, NULL);
	glfwGetWindowPos(windows[0], &xpos, &ypos);

	glfwSetWindowPos(windows[1], xpos + width + left + right, ypos);
	}

	glfwSetKeyCallback(windows[1], key_callback);

	glfwMakeContextCurrent(windows[1]);

	// While objects are shared, the global context state is not and will
	// need to be set up for each context

	glUseProgram(program);

	glEnable(GL_TEXTURE_2D);
	glBindTexture(GL_TEXTURE_2D, texture);

	glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
	glEnableVertexAttribArray(vpos_location);
	glVertexAttribPointer(vpos_location, 2, GL_FLOAT, GL_FALSE,
	sizeof(vertices[0]), (void*) 0);

	while (!glfwWindowShouldClose(windows[0]) &&
	!glfwWindowShouldClose(windows[1]))
	{
	int i;
	const vec3 colors[2] =
	{
	{ 0.8f, 0.4f, 1.f },
	{ 0.3f, 0.4f, 1.f }
	};

	for (i = 0; i < 2; i++)
	{
	int width, height;
	mat4x4 mvp;

	glfwGetFramebufferSize(windows[i], &width, &height);
	glfwMakeContextCurrent(windows[i]);

	glViewport(0, 0, width, height);

	mat4x4_ortho(mvp, 0.f, 1.f, 0.f, 1.f, 0.f, 1.f);
	glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
	glUniform3fv(color_location, 1, colors[i]);
	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

	glfwSwapBuffers(windows[i]);
	}

	glfwWaitEvents();
	}

	glfwTerminate();
	exit(EXIT_SUCCESS);
	}